Cloverleaf design obsolete, except in Pennsylvania

CARPENTER

October 26, 2004|By Paul Carpenter Of The Morning Call

"Are we there yet?"

Those words are dreaded by any parent who ever took a road trip with young children.

Such questions do not usually come from adults, but in the early stages of our journey out West, just 20 miles into Virginia on Interstate 81, which covers 320 miles before it hits Tennessee, my wife asked, "Are we still in Virginia?"

The last time my wife had accompanied me on a coast-to-coast car trip was in the 1960s, when she did not yet have a driver's license and our kids were little. It took two whole days to get to San Francisco.

This time, with my wife helping with the driving, I figured we could do better, even with a trailer in back.

We didn't. Still, there are good reasons to drive instead of fly. For one thing, you can't take a motorcycle on a plane.

I'll skip other gruesome details of this trip and mention some good parts, such as my wife's acknowledgement that, had we flown, we never could have toured the Sedona, Ariz., area, one of the most spectacularly beautiful places on the planet. Also, in Los Angeles, we had a great time visiting three of the world's seven greatest grandchildren.

Shortly after returning to the Lehigh Valley, I used the Interstate 78 death trap at Fogelsville. (Some people use a euphemism, "interchange cloverleafs," for these things.)

As I watched people playing dodge ball with each other, using motor vehicles, it occurred to me that I did not recall seeing cloverleafs west of the Mississippi River.

California has awesome traffic problems but uses a simple design on most freeway interchanges. You use a parallel exit ramp to get off and a similar ramp to get on. More complex intersections require more elaborate ramps, but rarely a cloverleaf.

The ramps intersect crossing roads at traffic lights or stop signs. They are a pain, but not as bad as cloverleafs.

Also, each cloverleaf wastes land, a particular problem in L.A., where land can go for upwards of $1 million an acre.

In April, the Los Angeles Times reported that "the cloverleaf interchange has outlived its usefulness" and California is spending millions to replace the things. "The cloverleaf's biggest flaw," the story said, "is that motorists merging onto a freeway, and drivers trying to get off, converge on the same short length of road, creating a gauntlet of speeding vehicles battling for a few precious gaps in traffic."

The story characterized a typical cloverleaf as a "hair-raising motorist mosh pit."

That brought Fogelsville to mind, so I took my cloverleaf questions to Dean Schreiber, director of the Bureau of Design in the Pennsylvania Department of Transportation.

"We have very few opportunities for cloverleaf design any more," he said, noting PennDOT favors "flyover ramps" at interchanges with heavy traffic volumes, such as intersections of two super highways. He said flyover ramps require "three-tier interchanges."

When big highways cross smaller roads, Schreiber said, "diamond interchanges" can be used. That is the design, popular around L.A., that uses stop signs and traffic lights.

"The cloverleaf may work," he said, when there is more traffic than can be handled by a diamond but not as much as that requiring flyover ramps.

PennDOT is still building the things, as evident at Routes 22 and 33, where a new death trap opened just three years ago.

I hope Pennsylvania joins other states in trying to get rid of them. (The only thing crazier than a cloverleaf is a traffic circle, but that's a problem for New Jersey to work out.)

In the meantime, if my wife happens to join you on a coast-to-coast car trip (with a trailer), and if you get her to take a turn driving, I do not recommend asking her to negotiate a cloverleaf in busy traffic.